From be8806c28f95d3dcb1f677245e2f840b7aeb9642 Mon Sep 17 00:00:00 2001
From: Mike Shoup <mike@shoup.io>
Date: Wed, 3 Jul 2019 19:52:24 -0600
Subject: [PATCH] Add hops

---
 src/humulus/filters.py                  | 27 ++++++++++++++++++++-----
 src/humulus/templates/recipes/info.html |  2 ++
 tests/conftest.py                       |  2 +-
 tests/test_filters.py                   | 17 ++++++++++++++++
 4 files changed, 42 insertions(+), 6 deletions(-)

diff --git a/src/humulus/filters.py b/src/humulus/filters.py
index 010a927..8c13d19 100644
--- a/src/humulus/filters.py
+++ b/src/humulus/filters.py
@@ -14,9 +14,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import math
+
 
 def recipe_og(recipe):
     """Returns a recipe's Original Gravity"""
+    if 'fermentables' not in recipe:
+        return '0.000'
     points = 0
     grain_points = 0
     # Loop through fermentables, adding up points
@@ -37,8 +41,8 @@ def recipe_og(recipe):
 
 def recipe_fg(recipe):
     """Returns a recipe's final gravity"""
-    if 'yeast' not in recipe:
-        return 0.0
+    if 'yeast' not in recipe or 'fermentables' not in recipe:
+        return '0.000'
     og = float(recipe_og(recipe))
     og_delta = 0.0
     # Adjust original gravity by removing nonfermentables (i.e., Lactose)
@@ -54,15 +58,28 @@ def recipe_fg(recipe):
             float(recipe['yeast']['high_attenuation'])
         ) / 200
     )
-    print(og - 1 - og_delta)
-    print(attenuation)
-    print(og_delta)
     return '{:.3f}'.format(
         round(1 + (og - 1 - og_delta)*(1 - attenuation) + og_delta, 3)
     )
 
 
+def recipe_ibu(recipe):
+    """Return a recipe's IBU"""
+    if 'hops' not in recipe:
+        return '0'
+    bigness = 1.65 * 0.000125**(float(recipe_og(recipe)) - 1)
+    ibu = 0.0
+    for h in recipe['hops']:
+        mgl = (
+            float(h['alpha']) * float(h['amount']) * 7490.0 /
+            (float(recipe['volume']) * 100.0)
+        )
+        btf = (1 - math.exp(-0.04 * float(h['duration']))) / 4.15
+        ibu += bigness * btf * mgl
+    return '{:.0f}'.format(ibu)
+
 
 def create_filters(app):
     app.add_template_filter(recipe_og)
     app.add_template_filter(recipe_fg)
+    app.add_template_filter(recipe_ibu)
diff --git a/src/humulus/templates/recipes/info.html b/src/humulus/templates/recipes/info.html
index 4c9ab2d..56e57c5 100644
--- a/src/humulus/templates/recipes/info.html
+++ b/src/humulus/templates/recipes/info.html
@@ -36,6 +36,8 @@
       <dd>{{ recipe|recipe_og }}</dd>
       <dt>FG</dt>
       <dd>{{ recipe|recipe_fg }}</dd>
+      <dt>IBU</dt>
+      <dd>{{ recipe|recipe_ibu }}</dd>
     </dl>
   </div>
   <div class="col">
diff --git a/tests/conftest.py b/tests/conftest.py
index f1fef06..917f4fd 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -251,7 +251,7 @@ def sample_recipes():
                 {
                     'alpha': '5.0',
                     'amount': '0.5',
-                    'duration': '10',
+                    'duration': '30',
                     'name': 'East Kent Goldings (UK)',
                     'use': 'Boil'
                 }
diff --git a/tests/test_filters.py b/tests/test_filters.py
index 3f10516..7a59cbd 100644
--- a/tests/test_filters.py
+++ b/tests/test_filters.py
@@ -19,8 +19,25 @@ from humulus.filters import *
 def test_recipe_og(sample_recipes):
     assert recipe_og(sample_recipes['lager']) == '1.054'
     assert recipe_og(sample_recipes['sweetstout']) == '1.038'
+    # Remove fermentables, verify 0 is returned
+    sample_recipes['lager'].pop('fermentables')
+    assert recipe_og(sample_recipes['lager']) == '0.000'
 
 
 def test_recipe_fg(sample_recipes):
     assert recipe_fg(sample_recipes['lager']) == '1.014'
     assert recipe_fg(sample_recipes['sweetstout']) == '1.015'
+    # Remove fermentables, verify 0 is returned
+    sample_recipes['lager'].pop('fermentables')
+    assert recipe_fg(sample_recipes['lager']) == '0.000'
+    # Remove yeast, verify 0 is returned
+    sample_recipes['sweetstout'].pop('yeast')
+    assert recipe_fg(sample_recipes['sweetstout']) == '0.000'
+
+
+def test_recipe_ibu(sample_recipes):
+    assert recipe_ibu(sample_recipes['lager']) == '26'
+    assert recipe_ibu(sample_recipes['sweetstout']) == '34'
+    # Remove hops, verify 0 is returned
+    sample_recipes['lager'].pop('hops')
+    assert recipe_ibu(sample_recipes['lager']) == '0'